"I applaud them doing that, I think it is very important for big companies like BHP to come out and say these things," Mr Cousins told ABC TV's The Business.

Because the ACF is a charity, people who make a donation can claim a tax deduction.

But there is a push within the Federal Government to make the ACF and other charities spend a slice of their money on non-activist efforts, or lose their charity taxation status.

The Minerals Council is backing the changes, which could neutralise its biggest opponents.

Advocacy an important part of policy and democracy: BHP

But in an extraordinary move, its biggest member, BHP, has written to charity groups saying it does not support the winding back of their tax advantages.

"We do not support changes that limit public advocacy to 10 per cent of funds, or requirements to spend 25 per cent of funds on environmental remediation," BHP told five environmental and community groups it wrote to.

"We have made our views known to Government," the company continued.

BHP also set out its broad support for the advocacy work of charities, describing it as, "An important contribution to public policy development and the democratic process".

The ABC approached the Minerals Council but it declined to comment.

At a recent meeting with BHP CEO Andrew Mackenzie, the ACF's Geoff Cousins told him that BHP should quit the Minerals Council altogether.

"You've got to match your action to the words or no-one is going to believe you," Mr Cousins said.

"They have gone a good way, I must be fair."

In 2010 a united campaign by the industry sank the then Labor Government's plans for a mining super profits tax.

But since then differences over climate policy have emerged.

BHP says it will complete a review of its membership of industry associations by the end of the year.

But activists hope next week's AGM is D-Day, with the board facing a resolution to dump the Minerals Council.

In her resignation from politics, Kelly O'Dwyer said she feared another miscarriage in Canberra, far from home. Her announcement is shocking for more than just party-political reasons, writes Emma A. Jane.